SMT Planar Power Transformers Take On 1500-V DC Isolation

A new line of 100- to 140-W surface-mount planar transformers targets high-density isolated dc-to-dc modules and discrete power supplies for use in telecom, datacom, and industrial control applications. The series is designed to meet either operational or basic insulation and 1500-V dc isolation. The units are optimized for frequencies between 200 and 500 kHz. They feature low resistance windings of less than 0.5 mΩ and high-end ac resistance performance. Offering substantial power density, the transformers feature low leakage inductance of less than 0.4 µH. They're designed for use in active-clamp forward-converter topologies operating from a wide-range telecom input voltage of 36 to 75 V. The PA0369 unit provides a regulated 100-W (3.3 V, 30 A) output while the PA0423 device has a 140-W (12 V, 11.6 A) output. Other versions are available for 5.0-V, 20-A and 26-V, 4-A outputs. The tranformers' surface-mount package is compatible with pick-and-place processes. All operate from −40°C to 125°C. The PA0369 and PA0423 transformers start at $2.85 and $3.15 apiece, respectively, in 100,000-unit quantities.